QTR-Quadtone RIP

Howard's approach intriqued me so I gave it a shot from another way. I used
the 'load curve' option but pasted in 50 points for each ink. I did this for
the 2200 K7-2880-Hanphotorag profile. I uploaded the qidf to the files
section under curves/2100-2200 and it's called k7-test.qidf.  I hope that is
alright with Jon and/or Roy. If not feel free to take it down.
By visually comparing the curves they look the same. I would be interested
in your remark about 'flat spots' Roy and see if this would apply to this
qidf?  The cone curves use up to 255 points but the qtr interface only
allows for 50 so I chose an equal distribution throughout to maintain
integrity. The K only has 46 points so it should be a direct match, but an
ink like Magenta had 254 so it has only 1/5th the points. But I would think
50 points would still be enough to prevent any flat spots.

Scott


On 1/16/07, Roy Harrington <roy@...> wrote:
>
>   Hi Carl,
>
> It's easy to do on the Mac, too. Just use:
> CURVE_K=k7_black.acv
> CURVE_LM=k7_ltmagenta.acv
> etc...
>
> Howard's idea is an interesting possibility. You could design the
> basic curve
> shapes this way and then linearize the result. The potential
> difficulty would be
> that you get some flat spots or extra wiggles in the density curve.
> Just because
> the look smooth doesn't mean the sum on the curves with different inks
> would
> also look that smooth. The linearize can fix only so much. In the
> specific example
> it probably would work well since they are designed from existing
> "good" profiles.
>
> Since the K7 inks are so close in density you can have the very large
> overlaps
> -- ie. 5 inks instead of just 3. There is also some benefit in the
> 2880dpi because its
> only one dotsize. At 1440 there will be 2 or 3 dotsizes used which
> results in more
> transitions.
>
> For anyone wanting to customize their own K7 ink profiles a very nice
> approach is
> to take advantage of the piezo k7 profiles and then build ICC profiles
> on top of
> them. This way you get full color management from screen to print with
> softproofing
> as well.
>
> Roy
>
>
> On Tuesday, January 16, 2007, at 03:14 PM, Carl Schofield wrote:
>
> > I assume this is only for the PC version or is there a way to use
> > the .acv curves with the Mac version of QTR?
> >
> > Carl
> >
> > On Jan 16, 2007, at 5:44 PM, Howard Shaw wrote:
> >
> >> Joost
> >>
> >> If you have a look at the Cone-made k7 curves (the 2880dpi ones) they
> >> are differently constructed to the type of curves that qtr makes.
> >>
> >> I've made a web page showing the difference and also how the Load
> >> curves
> >> facility in qtr can be used to emulate the type of curves produced by
> >> Cone's proprietary method.
> >>
> >> http://www.howardshaw.org/docs/k7-qtr/k7curves.htm
> >>
> >> The main difference is that the normal qtr curve creation method using
> >> density boundaries usually only allows 3 inks to overlap at a time
> >> whereas the Cone curves have upto 5 overlapping inks. On the basis
> >> that
> >> the more jets firing the better this should lead to a smoother print.
> >>
> >> Note that I do not have the K7 inks so this is a technical exercise
> >> only.
> >>
> >> Howard
> >>
> >> Joost Horsten wrote:
> >>> --- In QuadtoneRIP@yahoogroups.com <QuadtoneRIP%40yahoogroups.com>,
> "Scott Schroeder" <schrochem@...>
> >>> wrote:
> >>>
> >>>> I didn't mean you couldn't make curves. I was just saying you can't
> >>>> make curves that have the nice transitions and crossovers that are
> >>> in
> >>>> the supplied curves.
> >>>> This message will explain it better:
> >>>> http://tech.groups.yahoo.com/group/QuadtoneRIP/message/1165
> >>>
> >>> Thanks Scott, that explains your remarks indeed. But for my
> >>> information: does it make in practice REALLY any difference whether
> >>> you use these original PiezoBW curves in stead of making your own
> >>> curves with QTR? Since I'm printing on 2880 dpi with QTR/2100/UT3D
> >>> I've a hard time to find any grain in my prints. So, imho on that
> >>> aspect I expect there is little left to improve by going to 7 inks.
> >>> But even if so, do the details of the curve then still make a
> >>> difference on top of that? Or does the claimed smoothness of the NK7
> >>> inks ONLY appear with the custom PiezoBW curves?
> >>>
> >>> Joost
> >>>
> >
> >
> -
> Roy Harrington
> roy@... <roy%40harrington.com>
> Black & White Photo Gallery
> http://www.harrington.com
>
>  
>


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